Questions tagged [orbital-elements]

Orbital elements are a set of parameters that uniquely identify a specific orbit.

Filter by
Sorted by
Tagged with
0 votes
0 answers
45 views

Discrepancy between Keplerian Elements and real orbits? [closed]

I've written code for converting Cartesian State Vectors into Keplerian Orbit Elements (primarily from this answer). If we take a satellite 100km (X-axis) above the earth ($\mu = 398600km^3/s^2$) and ...
13ros27's user avatar
  • 101
2 votes
1 answer
83 views

Is it possible to change a satellite's eccentricity without changing semimajor axis (instantaneous maneuver paradigm)? What else needs to "give"?

I've been wondering whether it's possible to change a satellite's eccentricity without changing its semi-major axis. (I'm assuming instantaneous changes in velocity.) At first I thought that this ...
NeutronStar's user avatar
  • 1,027
2 votes
0 answers
85 views

How to calculate the ascending and descending node, as well as the true anomaly

I have the argument of perihelion, semi-major axis, eccentricity, inclination and mass. I have tried to look this up but get conflicting answers. Any help would be appreciated. (Edit) One physics ...
Starkie's user avatar
  • 31
2 votes
0 answers
34 views

How to determine Euler parameters?

I have two questions and I can't solve the second one. Here it goes: Question 1 Consider a normalized system of units where µ = 1, Earth radius = 6378.165 km is the length unity, and T = 806.81 s is ...
Alexandre Augusto's user avatar
0 votes
0 answers
41 views

Conversion of osculating orbital elements to TLE mean elements

I am looking for a method to resample TLE data, so they are regularly sampled. I wanted to use physical propagation to calculate elements at given time. However, the propagation of TLE by SGP4 returns ...
klobaska soslaninou's user avatar
2 votes
0 answers
104 views

What's the orbital inclination range Crew Dragons can reach if the Falcon 9 first stage is about to be recovered?

Inspiration4 was one of the very few orbital spaceflights in this century that didn't go to a space station. Yet, it reached an orbital inclination of 51.6°, same as the ISS. I believe this is due to ...
Old Man John's user avatar
1 vote
0 answers
110 views

Is my code correct to get six Keplerian parameters?

Is my code correct to get six Keplerian parameters? ...
jack's user avatar
  • 19
4 votes
1 answer
149 views

What is the current state of the art in converting between mean and osculating orbital elements?

I want to implement algorithms to convert from mean to osculating elements, and vice versa. I've been digging through Vallado's text (fourth edition), and under ...
Danny's user avatar
  • 215
2 votes
1 answer
271 views

Converting Keplerian Orbital Elements into 2D State Vectors in Unity C#

I have done an extensive amount of research into this topic, but am really struggling to implement the math necessary to pull this off correctly. Just for some context: I'm trying to create a semi-...
Ethan's user avatar
  • 21
1 vote
1 answer
91 views

Gibbs' method and position vectors' reference frame

As mentioned on this website https://www.studeersnel.nl/nl/document/technische-universiteit-delft/flight-orbital-mechanics-and-propulsion/chapter-05-preliminary-orbit-determination/4604099, we need to ...
Tug Speedman's user avatar
2 votes
1 answer
296 views

In MATLAB, Computing a new TLE/orbit following a delta-v impulse?

I have already worked on this project for a week, and I still can not solve this problem by myself. How can I update data for the SGP4 OrbitPropagator in Matlab's ...
Achilles chan's user avatar
1 vote
0 answers
183 views

Perifocal to ECI using Argument of Latitude

Suppose a satellite is orbiting Earth in a circular orbit. I know the following orbital elements: Inclination i, RAAN (Ω), Semi-major axis a (or orbit radius given that it is a circular orbit) ...
Suraj's user avatar
  • 157
3 votes
1 answer
461 views

Calculate velocity vector of elliptical orbit given the position vector at that point, the instantaneous speed, the true anomaly, and the inclination?

Sorry if this is obvious, but I am an amateur at orbital mechanics and trigonometry was never my strong suit. I would like to calculate the velocity vector at a point in an orbit given: position ...
John Doe's user avatar
2 votes
1 answer
159 views

(In ECI) How can I compute the RAAN of an orbit given the eccentricity vector, the declination of the orbiter at apoapsis, and the inclination?

I am working on a personal project, and I want to write a program to obtain the RAAN given the angle of the eccentricity vector to the X-axis (ECI) along the XY plane, the declination (angle from XY ...
John Doe's user avatar
0 votes
2 answers
399 views

Orbit prediction for satellites using the Kepler model

I would like to know how to model the motion of satellites in orbit using Keplerian, i.e. develop a simulation model that tracks paths of satellites using Keplerian orbits in Python?
Racky Alvin's user avatar
3 votes
2 answers
216 views

PseudoTLE creation

I am developing a script in python to obtain pseudo TLEs of a satellite, starting from its state vector. I have always used TLEs to propagate the satellite and predict its next pass over a ground ...
Luca Pizzuto's user avatar
1 vote
1 answer
222 views

Distance between a satellite and an orbit

I would like to compute the distance between a satellite and a specified orbit. For instance, for an orbit at 897 km altitude, 0 degree eccentricity, 99 degree inclination, and RAAN of 0 degrees on ...
Troy Rockwood's user avatar
2 votes
0 answers
190 views

How to use David Vallado's AstroLib to do reference frame conversions

Given a Keplerian Orbit description such as that in here: ...
ScottishTapWater's user avatar
3 votes
1 answer
119 views

Why does Earth's North Pole RA flip by ~180 deg around AD2000 relative to SSB? (JPL Horizons data)

Using JPL's Horizons API I see that the Earth's North Pole RA flipped by ~180 degrees quite suddenly around AD 2000. It was pretty stable around 180deg for at least 1000 years prior, and then remains ...
angst's user avatar
  • 143
2 votes
2 answers
174 views

How would one obtain the longitude of satellite at the apogee?

I know that apogee longitude is a design point in Molniya orbits. Given the classical orbital elements, how can I find this value?
EserRose's user avatar
  • 181
4 votes
0 answers
64 views

Where to get data for axis of rotation of solar system bodies?

Where can I get data for the axis of rotation of the (major) bodies of the solar system? For each solar system body, I want to get a unit vector of its axis of rotation (at a specified point in time). ...
angst's user avatar
  • 143
5 votes
2 answers
204 views

Why is there a 38.6 km Earth-Moon distance difference between Ephemeris types "Observer table" and "Vector table" on Horizons Web Application?

The image above is a screenshot from Horizons Web Application with the Ephemeris type: Observer Table. It shows the distance (delta) from the geocentric observer location to target Moon on April 15, ...
Cornelis's user avatar
  • 7,545
1 vote
0 answers
203 views

Osculating conic orbital elements: Comparing SPICE's oscelt to MATLAB's ijk2keplerian functions

I have been using the SPICE Toolbox and wanted to derive orbital elements from a state vector $X$ in ECEF coordinates [1] in order to define a circular orbit around Earth. To do so I need first ...
Loïc Poncin's user avatar
1 vote
0 answers
93 views

How to find the SMA starting from a given repetition factor?

I need a help for an orbit design problem. My constraint is that the height is 480 km, the repetition factor has to be Q = 245/16 and the orbit must be sun-synchronous. I would like to find the SMA ...
Sfusfina's user avatar
9 votes
1 answer
1k views

I'm building a CubeSat for a short 8-day mission in LEO followed by a fairly quick reentry, what range of orbits to consider?

The goal of this CubeSat mission is to demonstrate CubeSat construction, operation, and communication in Low Earth orbit for 8 days or longer. Why the short mission time? Because the mission lacks ...
Deko Revinio's user avatar
  • 1,476
2 votes
1 answer
301 views

Vernal equinox direction and origin of longitude difference?

I am trying to visualise satellite orbits from a top-down perspective on the Earth, with down as 0° longitude. I am getting confused as to which the reference direction is using the right ascension of ...
Ally's user avatar
  • 85
6 votes
1 answer
647 views

Major axis larger than total of apogee and perigee?

I am trying to calculate the apogee and perigee using the orbital elements. I am checking my results against CALSPHERE 1 (https://www.n2yo.com/satellite/?s=900). I am getting 7363599.5m as the semi ...
Ally's user avatar
  • 85
7 votes
0 answers
303 views

Can you identify this space travel related equation?

Does anyone recognize the equation carved on this object? The only hint I have is that the back side has the word "orbit" carved into it. It may be incomplete or incorrectly copied. My best ...
JRE's user avatar
  • 813
1 vote
1 answer
51 views

Finding the largest X/Y/Z component of an orbit (in terms of ECI) using orbital elements?

If I wanted to find the largest component of an orbit on a single axis, like finding where on the orbit a satellite would reach its highest X component (not specifically an apoapsis, just when the X ...
TheLazerCat's user avatar
1 vote
1 answer
128 views

What are the product terms shown here representing an orbit?

I can compute Kepler parameters from a given TLE using Skyfield. I am checking the satellite information from this website and the orbit is represented as $$ 546 \times 548 \text{ km} \times 53.1 \...
jkt's user avatar
  • 153
9 votes
2 answers
417 views

Why do the modified equinoctial elements use the semilatus rectum?

The classic orbit elements, $(a,e,i,\Omega,\omega,\nu)$, have annnoying singularities in their non-Keplerian perturbed dynamics at $i=0\pm \pi$ and $e=0$. So Arsenault, then Braucke & Cefola, then ...
J Peterson's user avatar
5 votes
1 answer
2k views

How can I get longitude of ascending node from satellite TLEs with Right Ascension of Ascending Node (RAAN)?

As the title says, the TLEs contains RAAN, from which I want to get the longitude of ascending node, as defined in the STK help file as shown in the figure. Is there an open source tool for python to ...
user47758's user avatar
2 votes
1 answer
177 views

Is it possible to determine the classical orbital elements for an Elliptic Repeating SSO?

As in the title, it is possible to have a repeatable Sun-synchronous orbit but with an elliptic eccentricity? If yes, which equations I have to consider to determine its classical orbital elements?
Frank's user avatar
  • 315
4 votes
1 answer
531 views

Plot ellipse using elements from TLE

I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center. EllipseCurve( aX : Float, aY : Float, xRadius : ...
Sourav Anand's user avatar
5 votes
2 answers
200 views

Relationship between osculating eccentricity and Brouwer-Lyddane short eccentricity

I was under the impression that the mean elements are given by taking the average over an orbital period of the satellite, i.e.: $e_{mean}(t) = \int_{t}^{t+T(t)}e_{osc}(t')dt'[0.367in]$ where $T(t)$ ...
Jan Lynn's user avatar
  • 169
2 votes
0 answers
189 views

Is electric propulsion feasible for human spaceflight?

I have been reading a lot about electric propulsion and was wondering if it would be feasible for human spaceflight. It is really efficient but it takes a while to get to the desired speed. Would it ...
The Rocket fan's user avatar
3 votes
1 answer
813 views

How do I correctly convert State Vectors to Orbital Elements to State Vectors at t (sec since epoch) in 2D?

I am following Rene Schwarz' formulas and I've verified my calculations work using the converter by Tony Dunn. State Vectors to Orbital Elements Orbital Elements to State Vectors Convert between ...
Wafer's user avatar
  • 167
2 votes
1 answer
174 views

Predicting Satellite Flyover Calculations by Hand

Recently I used transit-finder.com to get a really cool picture of the ISS transiting the sun. The prediction from the website was spot-on. Since then I'm absolutely fascinated by how the prediction ...
ken's user avatar
  • 21
2 votes
2 answers
411 views

Is there a parameter that describes the angle between the spacecraft's position and the sun angle or direction of the Earth's motion?

I am trying to design an Earth flyby for gravity assist in GMAT, and I know from theory that the spacecraft should pass in front of a planet with regard to its heliocentric direction of motion in ...
kardalos's user avatar
  • 339
3 votes
1 answer
200 views

What maneuvers could be useful to move between two sun synchronous orbits with different times?

Consider two sun-synchronous orbits with similar orbital elements, except for their times. For example 8h and 9h orbits. Their semi-major axes (a), inclinations (i), and eccentricities (e) are the ...
pathfinder_EOS's user avatar
12 votes
2 answers
2k views

Why does a launch due south (180° azimuth) not translate into a polar orbit from Vandenberg?

I found this image showing the allowable launch azimuths for Vandenberg AFB and I was wondering why a 180° launch azimuth doesn't match a 90° inclination orbit. This led me to question the equation ...
Matt's user avatar
  • 121
3 votes
1 answer
239 views

Different/better ways to calculate the shadow region passage of the satellite and the effect of orbital elements, other than shadow cone technique?

The NASA Technical Publication Method for the calculation of spacecraft umbra and penumbra shadow terminator points; TP-3547 describes the following: A method for calculating orbital shadow ...
Astrolien's user avatar
  • 569
3 votes
1 answer
526 views

Why is the eccentricity vector used to describe near-circular orbits?

When dealing with near-circular orbits I've seen the usage of the eccentricity vector defined as $$(e_x,e_y) = (e\cos\omega, e\sin\omega)$$ I've seen this in Schaubs' "Analytical mechanics of ...
JuliusC's user avatar
  • 163
4 votes
1 answer
225 views

What type of galactic orbit will the Voyager probes have?

I know that they will eventually get close (within 10,000 light years) of our solar system, but will the orbit be circular or elliptical, around how much eccentricity, what would be a reasonable ...
Starship - On Strike's user avatar
4 votes
2 answers
374 views

Compute orbital parameters from transverse and radial velocity at a given distance from the focus

I've been pulling my hair on this problem for a couple of days now, researched a lot but have not been able to find results. Basically I'm writing a program capable of drawing a transfer orbit between ...
Canleskis's user avatar
-1 votes
4 answers
887 views

How can I find the x, y position of apogee and perigee, if I only have the value of distance vector (position) and velocity vector?

I am currently working on a 2D space simulator where I have two bodies; one is still and other is an orbiting object, which I can also control like a rocket. I'm using the Newton's gravity: $F = \...
user325's user avatar
  • 29
2 votes
2 answers
754 views

Does the James Webb Space Telescope have a Two Line Element set?

How do you track the position of the James Webb space telescope? Does it have its own TLE, or...?
lawndownunder's user avatar
3 votes
1 answer
501 views

When calculating the six Keplerian Orbital Parameters, why do we need both Eccentricity AND the Semi-Major Axis? Doesn't one tell you the other?

Perhaps I am misunderstanding elementary math, but.... How is it possible to know the eccentricity of an ellipse (e) but not the semimajor axis (a)?
Kurt Hikes's user avatar
7 votes
1 answer
1k views

Why does the eccentricity vector always point towards the periapsis of an orbit?

I hope you know that eccentricity can be derived from the position and velocity vectors of a spacecraft (only applies to a two body problem) through this formula : $$\textbf{e} = \frac{\dot{\textbf{r}}...
John's user avatar
  • 113
5 votes
2 answers
363 views

Required Orbital Components to Fully Define Orbit

As a follow-up to this question. I have this JSON coming back from the ESA's DISCOSweb API: ...
ScottishTapWater's user avatar

1
2 3 4 5